This information is provided free of charge by the Department of Industrial Relations
from its web site at www.dir.ca.gov. These regulations are for the
convenience of the user and no representation or warranty is made that the information
is current or accurate. See full disclaimer at http://www.dir.ca.gov/od_pub/disclaimer.html.

(a) General. Every establishment performing dry grinding, dry polishing, or buffing shall provide suitable hoods or enclosures that are connected to exhaust systems which are run continuously during operations.

Exception: When the concentration at the operator's breathing zone of any airborne contaminant generated by such an operation is below the applicable
limit prescribed in Section 5155 or any other section of Title 8.

(b) Hood and Branch Duct Performance Requirements.

(1) Hoods connected to exhaust systems shall be used, and such hoods shall be designed, located, and placed so that the dust or dirt particles shall fall or be projected into the hoods in the direction of the air flow. No wheels, discs, straps, or belts shall be operated in such manner and in such direction as to cause the dust and dirt particles to be thrown into the operator's breathing zone.

(2) Wheels and belts shall have not less than the minimum exhaust volumes shown in the following tables:

(3) Cradles requiring partial enclosures to house the complete operation shall be ventilated sufficiently such that a minimum air velocity of 150 feet per minute shall be maintained over the entire opening of the enclosure.

(c) Hood Design.

(1) Vertical-spindle disc grinders shall be encircled with a hood so constructed that the heavy dust is drawn off a surface of the disc and the lighter dust exhausted through a continuous slot at the top of the hood as shown in Figure V-1.

(2) Exhaust hoods for floor stands, pedestals, and bench grinders shall be designed as effective as Figure V-2. The adjustable tongue shown in the Figure shall be kept in working order and shall be adjusted within one-fourth inch of the wheel periphery at all times.

(3) Swing-frame grinders shall be exhausted in the same manner as provided for cradles, and shall be provided with exhaust booths as indicated in Figure V-3.

(4) Hoods for polishing and buffing and scratch-brush wheels shall be constructed to conform as closely to Figure V-4 as the nature of the work will permit.

(5) Cradle grinding and polishing operations shall be performed within a partial enclosure similar to Figure V-5. The operator shall be positioned outside the working face of the opening of the enclosure. Cradle enclosures shall be ventilated sufficiently such that a minimum air velocity of 150 feet
per minute shall be maintained over the entire opening of the enclosure.

(6) Hoods for horizontal single-spindle disc grinders shall be constructed to conform as closely as possible to the hood shown in Figure V-6.

(7) Horizontal double-spindle disc grinders shall have a hood encircling the wheels and grinding chamber similar to that illustrated in Figure V-7. The openings for passing the work into the grinding chamber should be kept as small as possible, but must never be less than twice the area of the branch outlets.

(8) Grinding and polishing belt hoods shall be constructed as close to the operation as possible. The hood should extend almost to the belt, and 1-inch wide openings should be provided on either side. Figure V-8 shows a typical hood for a belt operation.

(d) Portable Operations.

Portable grinding, polishing, and buffing operations, whenever the nature of the work permits, shall be conducted within a partial enclosure over which an average face air velocity of not less than 200 feet per minute shall be maintained, or a low volume, high velocity local exhaust hood attachment shall
be used. (Title 24, T8-5152)

NOTE: If grinding wheels are used for disc grinding purposes, hoods must conform to structural strength and materials as described in 9.1.Entry Loss =0.45 velocity pressure for tapered takeoff.
Note: If grinding wheels are used for disc grinding purposes, hoods must conform to structural strength and materials as described in 9.1.